M12 Temperature Sensor

For many years sensors used in high reliability applications, such as those used in aerospace and military applications, relied upon connectors such as the Mil-C-5015 or MIL-C-38999 connectors that provided high reliability and secure connections but at a high price. With the expanded use of industrial automation systems however, the number of sensors used have increased dramatically, driving the need for a reliable, cost effective connection system for these sensors.

The development and release of IEC Standard 61076-2-101, “Connectors for Electronic Equipment” opened the door for a connection system that is reliable, reasonably priced, and readily available. That connector, often referred to as an “M12” connector, is now a staple in many sensing and control applications.

Omega Engineering is leading the way in adapting this connector system to a variety of temperature sensor products including Thermocouples, Resistance Temperature Detectors (RTDs) and Thermistor sensors. These sensors are being used in a growing number of applications including food and dairy processing, biopharmaceuticals and industrial automation.

Standard convention is to place the connector with exposed pins (see Figure 3) on the non-powered (sensor) side of the connection so that any unintended contact with the operating current will not occur. For this reason, Omega’s temperature sensor products all include a “plug” style connector on the product as shown in Figure 3.

The extension cable, which connects the sensor to the system, provides the operating current and returns the sensor’s signal, has a socket style connector (see Figure 4). This connector can be a molded connector or one that is mechanically assembled. Figure 4 shows a typical mechanically mounted socket style connector.

In addition to the ease of installation and maintenance, M12 connections provide the additional benefit of providing sealed connections that can be used in wet or wash down environments. Processes such as those used in the food, dairy and pharmaceutical industries are exposed to frequent wash downs where the M12 connection protects the wire connections from attack and corrosion by the chemicals used in these processes.

M12 connectors are available in a variety of configurations. Omega has adopted the commonly used “A-coded”, 4-pin connector style (see Figure 5) for all of our sensors. This arrangement provides the greatest flexibility for the customers since all of our M12 enabled RTD sensors are made with 4-wire construction (so they can be used with any 2, 3 or 4-wire system) and thermocouples can be made with single or dual junctions.

Omega Engineering’s family of M12 enabled sensor products are offered with machined stainless steel or injection molded housings. Machined stainless steel housings can be supplied with a variety of mounting threads or with non-threaded housings to suit the application. Omega also supplies a line of 3A approved tri-grip sensors that can be used in Clean-In-Place (CIP) systems typically used in food, dairy, fermentation and pharmaceutical industries.


Omega’s growing family of M12 enabled sensors includes all of the common styles of temperature sensors including RTDs, Thermocouples and Thermistor sensors. Keeping with Omega’s emphasis on providing measurement solutions to meet nearly any customer application, we offer a wide selection of M12 extension cables and accessories. These include the typical PVC and Polyurethane cables, as well as a new line of fully compensated thermocouple cables. A typical PVC insulated cable with over molded connectors is shown in Figure 6. In order to provide a completely customizable line of extension cables, Omega also offers extension cables utilizing mechanically assembled connectors to which we can attach a wide variety of cable constructions, as well as enhancements such as steel over-braid and square locked hose for improved mechanical protection or electrical shielding (see Figure 7).

Sensor Type	Mounting Style	Housing Style	Model Number Series
RTD (Pt10or Pt1000)	Non-Threaded	Machined SST	PR-21A, PR-26A
	1/2NPT		PR-21B, PR-26B
	3/8NPT		PR-21C, PR-26C
	1/4NPT		PR-21D, PR-26D
	M8x1		PR-21E, PR-26E
	M10x1		PR-21F, PR-26F
	G1/2 BSPP		PR-21G, PR-26G
	G1/4 BSPP		PR-21H, PR-26H
Thermocouple (Types J and K)	Non-Threaded	Machined SST	M12…-A
	1/2NPT		M12…-B
	3/8NPT		M12…-C
	1/4NPT		M12…-D
	M8x1		M12…-E
	M10x1		M12…-F
	G1/2		M12…-G
	G1/4		M12…-H
RTD (Pt100 or Pt1000)	Non-Threaded	Molded Nylon	PR-22, PR-31
Thermocouple (Type J or K)	Non-Threaded	Molded Nylon	M12M…
RTD (Pt100)	Tri-Clamp	Machined SST	PRS-S-M12
Thermocouple (Types J and K)	Tri-Clamp	Machined SST	TCS-S-M12
Thermistor	Tri-Clamp	Machined SST	THS-S-M12

M12 Cables and Accessories for use with the above sensors include the following:

Accessory	Model Number	Description
Extension Cable	M12CM-EXTP-…	Fully Compensated M12 Thermocouple cables with PVC insulated cables and TPU over molded connectors (85°C Max)
Extension Cable	M12CM-EXTT-…	Fully Compensated M12 Thermocouple cables with Teflon insulated cables and LCP over molded connectors (250°C Max)
Extension Cable	M12CM-EXTT-4-…	4-Wire M12 Teflon extension cable with LCP over molded connectors for RTDs and other process sensors
Extension Cable	M12C-PUR	Polyurethane cable with Molded M12 connector one end or both ends
Extension Cable	M12C-PVC	PVC cable with molded M12 connector one or both ends
Special Extension Cable	M12CFM-	Extension cables with mechanically assembled M12 connector one or both ends, variety of cable materials as well as steel braiding or hose options
Field Mountable Connectors	M12-	Field installable connectors, straight or right angled, plug or socket style
Spring Loading Kit for Thermowells	¼-SLK	Allows ¼” probes to be spring loaded into .260 bore, ½” NPT or NPSM threaded thermowells
Spring Loaded 1/2x1/2	SLF-1/2-1/2-1/4	Allows ¼” probes to be spring loaded into .260 bore, 1/2NPT or NPSM threaded thermowells with 1/2NPT thread for attaching enclosure
Stainless Steel Compression Fitting	SSLK	Stainless Steel fixed location compression fitting
Brass Compression Fitting	BRLK	Brass fixed location compression fitting